It is very common practice in today's society to obtain a beverage, whether it be coffee, tea, a soft drink, milk, juice, and so on, from a source other than one's home. Such sources include donut shops, variety stores, fast food outlets, coffee trucks, and a large number of like places. Often, such beverages are obtained while travelling, very often while travelling in a car, and will be consumed while travelling. In any event, it is desirable that the drinking vessels in which they are sold be covered for at least two reasons. Firstly, covering the cup would preclude spilling the contained beverage. Secondly, if the contained beverage in the cup is hot, the lid will help insulate the beverage from the surrounding and ambient air, thus keeping some of the heat in.
The term cup is used to denote a drinking vessel, a container, a glass, a bowl, a dish, a mug, a tumbler, or anything similar. Such cups can contain food, hot beverages, or cold beverages, or anything similar.
Such lids are typically made of thin inexpensive plastic, since they are meant to be disposable. Since they are made of thin plastic, it is fairly easy to tear a portion of the lid such that an opening is created. This opening would allow liquid within the cup to be consumed while still keeping most of the lid in place. Originally, cup lids had no specific provision for removal of a piece of the lid in order to drink to contained beverage. Instead, a piece of the lid was merely ripped off, usually while the cup lid was in place over the cup. The ripping of the cup lid was fairly random given that there was no specific part of the lid that was adapted to be removed. Often, too much or too little of the lid was ripped and removed. If too little was removed, some more could be removed until the desired size opening is achieved, however, this makes the process unnecessarily difficult, and does not guarantee that too large an opening won't result. If the cup lid is torn and too large an opening results, then it is more likely that beverage contained with in the cup would spill from the cup.
Cup lids are generally made from a thin sheet of extruded polystyrene material. This polystyrene sheet has associated with it orientation lines that are caused by the extrusion process. The polystyrene material readily tears along these orientation lines, but does not tear readily in other directions. In order to form the cup lids from the polystyrene sheet, the polystyrene is either run through a thermoforming machine immediately after it is extrudedor the polystyrene may be firmly rolled and stored and then run through a thermoforming machine.
In the molding machine, the polystyrene sheet is placed over a male mold. The polystyrene is shaped to the mold by means of suction through small openings in the mold. Pressurized air on the other side of the sheet forces the polystyrene against the mold, so that it generally conforms to the entire outline of the mold.
More recently produced cup lids often have some means by which a flap portion of the lid, which is to be torn away and thereby produce an opening, is defined by plurality of score lines or the like. Typically, a tab that is an extension of the flap protrudes outwardly from the edge of the cup lid. To tear the flap from the remainder of the lid, thus creating an opening for drinking, the tab is grasped and lifted upwardly. The lid begins to tear at the base of the tab and continues to tear along the imprinted score lines. Sometimes, a cup lid will have notches or slits at the base of the tab, which lead into the score lines. Such notches or slits ensure that the tear or tears in the cup lid are started in the correct spot.
There are a number of problems with using the score lines method of defining an opening in a cup lid. Firstly, it is difficult to produce cup lids with accurate score lines given that such a thin plastic material is used.
The general shape of the cup lid is of course circular, with a substantial portion of it being a generally planar body. There is also a circumferential displaced lip depending from the generally planar body, with the lip adapted to fit over the edge of a styrofoam or paper rolled-edge cup. The planar top portion of the lid typically has an upwardly directed angular channel that forms an annular lip that is adapted to receive the top portion of the cup. The planar portion of the lid is generally recessed slightly below the top of the cup. There is also typically a small ridge within the top planar portion of the lid that is located so as to preclude the tearing of the opening such that the opening will not become too large.
Another feature found on many cup lids is a means for holding the flap open so that a person can drink from the cup through the opening in the lid without the flap getting in the way. In use, once the flap is torn back thus creating an opening, it can then be folded over onto the lid where a portion of the flap is received by a mating portion of the lid. This mating portion of the lid is shaped so as to retain a portion the flap in frictional relation therewith, in the folded back position.
It has been found that there is a disadvantage in making the opening in the cup lid large, as most are. A person must be very cautious in order to drink from the cup without spilling, and must cover the opening entirely with their mouth while drinking.
It has being found that in many prior art type lids, when a portion of the flap is retained by the cup lid usually the end portion of the flap--the middle portion tends bow out, or alternatively the lip portion of the flap tends to stick up. These problems are more prevalent in cup lids having a large flap. In any event, part of the flap can be in the way of a person who is drinking from the cup--usually in the way of the person's nose. Such a problem could be precluded by having a smaller opening in the lid and therefore a smaller flap, with an improved means for holding the open flap on to the cup lid.